The evolution of handle designs for hand tools and other ansate implements included substantially cylindrical structures intended primarily for providing a comfortable hand grip. Generally, tool handles of the prior art such as those used for screwdrivers included a concave or reduced diameter portion adjacent the tool shank for receiving the user's thumb as typically shown in U.S. design patents nos. 143,931, 259,237, 261,610 and U.S. Pat. No. 3,586,080. In addition, some of those handles had a noncircular circumference so that the tool would not roll when placed on an inclined surface; similar handle designs were shown in U.S. design patents nos. 154,326 and 248,922.
A deficiency of the aforementioned tool handles was that they were not designed specifically for providing rotational leverage, as for driving a tool shaft. Another shortcoming of the prior art tool handles was that they relied upon a frictional gripping action. It should be apparent that the tenaciousness of the grasp was necessarily dependent upon the coefficient of friction between the material of which the handle was constructed and its surface configuration, as well as upon the muscular strength developed by the user's hand. Thus, the rotational driving force of a screwdriver, for instance, was diminished if the tool was being used by a mechanic having grease laden hands. Similarly, it should be appreciated that heavy gloves worn by a linesman or deep sea diver would affect the tool handle gripping action and the resultant torsional force applied. In a similar manner, the operation of hand tools and utensils of the prior art requiring a frictional force drive was severely limited when used by individuals having arthritic hand conditions.
The present invention overcomes the drawbacks of slippage inherent in the handles of the prior art and furthermore delivers rotational power through a gear drive principle.